I don't get why the 45 is considered such a bargain. It covers a much smaller image circle than a FF nifty-fifty, but costs three times as much.

Mount a larger, heavier 50mm from FF onto your M43 body and you get drastically worse quality than the 45, then realize that 200 pounds they want for it represent fantastic value.

Actually, I've done that and the quality was quite good. Remember, with a FF lens on an MFT body, you're only using the center of the lens, the sharpest part. If the lens was made for digital, it will do just fine on MFT. The downside is no AF.